To meet the demand for the development of a color photographic photosensitive material having high sensitivity and using fine silver halide grains, many improved color photographic photosensitive materials have been proposed. One photosensitive material that complies with this demand is described in British Pat. No. 923,045. The material comprises a high-sensitive emulsion layer that contains a non-diffusion coupler and a discrete low-sensitive emulsion layer that contains another non-diffusion coupler which forms the same color. According to the British patent, by designing the high-sensitive emulsion layer to provide a lower maximum color density, increased sensitivity can be achieved without sacrificing the graininess.
But the ever increasing demand for providing the taking color photographic photosensitive material with even higher sensitivity has compelled using in emulsion layers coarse silver halide grains having low graininess and/or a coupler having great coupling speed. Under these circumstances, the method of Biritsh Pat. No. 923,045 is no longer satisfactory for achieving improved graininess, and so attempts have been made to provide further improved graininess. Japanese Patent Publication No. 15495/74 describes one such attempt. On page 4 of the published specification, this patent states that improved graininess can be provided by forming a gelatin layer between the high-sensitive and low-sensitive emulsion layers described in British Pat. No. 923,045. This method can improve the graininess of the low-density area, but it has significant adverse effect on the gradation. If the impaired degradation is remedied by a conventional technique, say, by increasing the size of the silver halide grains, the sensitivity of the low-sensitive emulsion layer is increased, but then the graininess of the medium-density area that is particularly important for practical purposes is decreased. Furthermore, the density of the color image formed by the multi-layer color photographic photosensitive material incorporating the proposal of Japanese Patent Publication No. 15495/74 is not stable against the variation in the developing conditions, such as pH, temperature and time.
Japanese Patent Publication No. 15495/74, as well as Japanese Patent Application (OPI) No. 7230/78 (the symbol OPI as used herein means an unexamined published Japanese patent application describe a process wherein the high-sensitive and low-sensitive emulsion layers of British Pat. No. 923,045 are interposed by a first medium-sensitive silver halide emulsion layer having lower color density and a second medium-sensitive silver halide emulsion layer also having lower color density but which contains a DIR compound. But this method is also not desired since the increased use of silver halide causes increased fog for one thing and results in increased consumption of precious silver resources for another.